Managing excess water in the Pilbara

Managing excess water in the Pilbara

BHP has extensive iron ore operations in Western Australia’s Pilbara region. The region is underpinned by aquifers of groundwater that support local ecosystems and have important spiritual and cultural significance for Indigenous communities.

To access the ore, groundwater is pumped from wells in and around the pit. This water is used to meet operational needs, but substantial surplus water volumes remain above those requirements. The management of these volumes of excess water requires a deep, technical understanding of the water resource, its behaviour and interactions with the environment and areas of cultural importance.

BHP’s WAIO Water Management Standard establishes a hierarchy of water use that aligns with local regulatory guidance. Our preference is to return surplus water to the aquifer to minimise impacts to springs, ecosystems and/or spiritual and cultural values as a result of groundwater extraction. Returning water to the aquifer occurs using sumps and wells, a process known as managed aquifer recharge.

This process of managed aquifer recharge is technically challenging with practical limitations and, as a result, excess water can be discharged to creeks and rivers. Our intent is to minimise prolonged discharge to surface waters, which may create new habitats that may become dependent on ongoing irrigation.

Returning water to aquifers requires identifying and testing suitable aquifers to ensure there is sufficient capacity to introduce the excess water. The field-testing is a lengthy process over a large area that requires additional regulatory approvals.

The return of excess water to the aquifer is in operation at Mining Area C (injection borefield and infiltration basin), Jimblebar (injection borefield and infiltration basin) and Eastern Ridge (infiltration basins and ponds) operations. The quantity of excess water is forecast to rise and further aquifer return schemes are in development or under investigation. We also remain open to other uses for excess water, including by third parties (such as for agriculture), where the use would be sustainable and socially acceptable.